The Inner Lives of Fish

February 11, 2012

The Smithsonian's National Collection of Fishes has an estimated four million individual specimens, representing more than 70% of the world's fish species. "X-Ray Vision: Fish Inside Out," an exhibit that opened at the National Museum of Natural History in Washington last weekend, captures these aquatic wonders in X-rays. The prints offer a glimpse into the intricate inner workings of the fish and, for scientists, allow a detailed study of their anatomy and evolutionary development without dissection.

Here are some images from the exhibit, which will be traveling to sites around the country through 2015.

Viper Moray

These eels are legendary predators on coral reefs. Here, you can see a second set of jaws in the "throat"—these are the gill arches, which are present in all fish. Gill arches support the gills, the major respiratory organs of fish.

ENLARGE

Lookdown
National Museum of Natural History, Smithsonian Institution

Lookdown

Because of its sloped head and the enlarged crest on its skull, the lookdown appears to look down as it swims. These fish, found in the warm waters on the east and west coasts of the U.S., often swim in small schools.

Long-Spine Porcupine Fish

When threatened by a predator, the porcupine fish inflates its body by pumping water into its stomach. The body becomes a round, rigid ball bristling with spines. But when the fish is relaxed, the spines lie flat against the body.

Dhiho's Seahorse

Just over 1 inch long, this elegant fish, found only in the waters around Japan, is readily identified as a seahorse by its characteristic head. The body ends in a tail that can curl around and hold on to algae or coral.

Wedge-Tail Triggerfish

This fish discourages predators by erecting two sharp dorsal spines at the top of its head: one that is large and thick in front, and a shorter spine behind that. The second spine is the "trigger," which locks the first one in place.

Torrent Loach

The two sets of crescent-shaped fins on the underside of torrent loaches work like suction cups to help them stay in place on a rock or streambed in rapidly moving waters. This specimen belongs to a newly discovered species that has not yet received a scientific name.

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